Ground trainer for aircraft



May 17, 1949. R. B. BUCHANAN GROUND TRAINER FOR AIRCRAFT 3 Sheets-Sheet l Filed Dec. 28, 1946 INVENTOR n.5. BUCHANAN M ATTORNEY k. ku Ob May 17, 1949. R. B. BUCHANAN GROUND TRAINER FOR AIRCRAFT 3 Sheets-Sheet 2 Filed Dec. 28, 1946 EN QN www May 17, 1949. R. B. BUCHANAN GROUND TRAINER FOR AIRCRAFT 3 Sheets-Sheet I5 Filed Dec. 28, 1946.

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MDM] NOMI /Nl/ENTOR RB. BUCHANAN @6. M'

ATTORNEY.

Patented May 17, 1949 [TED STATES PATE NT OFFICE GROUND TRAJNER .FOR AIRCRAFT Russell B. Buchanan, Lynbrook, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of 4'New lork Application December 28, 1946, Sera'l'No. 1718,'917

1.3 Claims.

This invention relates to Van operational flight trainer and more particularly to circuits and apparatus for simulating the control of the armament 1of an airplane.

An airplane of the fighter type, which the trainer vof this invention is designed to simulate, may be provided with a plurality of guns', with a plurality of rocket iiring devices and with bomb releasing mechanism. For the sake of safety when the airplane is 'on the vcarrier deck, aireld or in formation night but not in actual combat, the guns are not charged with shells and the bombs are not armed.

The charging mechanism oi the guns of the airplane is hydraulically operated by pressure supplied from the hydraulic system of the airplane under thefcontrol of gun chargers located on the 'pilots pedestal in the cockpit and operable by the pilot. A plurality of these gun chargers may be provided, each capable of controlling the cl'iarging of one or more guns. The operation of such vchargers is simulated in the trainer under Vconsideration in the manner fully disclosed Yin my Patent No. 2,459,867, granted January 25, 1949, on an application 'Serial No. 622,066, filed October l2, 1945.

In the airplane the rocket ring mechanism is arranged so that the eight rockets carried by the airplane may be released two rockets at a time; in two groups of two rockets each followed by a group of four rockets; ,in a lsingle group of two rockets followed by the remaining six rockets or 'in a salvo of all eight rockets. To accomplish rthis a rocket selector is provided which may be vset into the four selection positions above indicated and which may be released under spring power, step by step in response to the operation yof the rocket trigger. When turned to the extreme right, one pair of Vrockets will be fired when the rocket trigger is depressed and the selector 'will be released to turn one step in a clockwise direction. Upon the next depression of the rocket trigger, a second -pair of rockets will be fired and the selector will be released to turn a vsecond step in a clockwise direction. Upon the Anext depression of the rocket trigger, a third pair of 'rockets will -be fired and the selector will be released to turn a third step in a clockwise direction and upon the next depression of the rocket trigger, the iinal Apa-L'lr-of rockets will be red. It will be noted that if the selection is initially started from the second step position, two rockets may be fired -in such position and the succeeding position and tour rockets in the last position; that ii the selecterfis initially set to the third step switch and press the bomb trigger.

position, two `rockets may 'be fired in such position and the remaining rockets in the last position and that 'if the selector is initiallyset zto its fourth step position, 'all 'o'f the rockets will be red in salvo when `the trigger is depressed.

The lbombs on an actual airplane Yare arranged to be xdropped either Lsafe or armed 'as determined by the pilot. The 'two bombs -carried on the wings and the fuselage or belly bomb may Aall *be A'dropped simultaneously, singly,` or in a two land one combination as determined by the pilot. A T handle is Ialso provided bym'eans of which `the pilot may 'opera-te the' releasing mechanism for the fuselage bomb. This 'handle is lalso used to safety the fuselage bomb. However, this bomb can be ldropped safe `only by the use of the T handle and when released bythe electric 'control is always in an armed condition.' :The pilot may drop the wing'bombs in a sare condition by 'Operating 'a `wing bomb key to a safe position, that is open, and will then close an RT or LT switch or both. "He will next close the master armament If he desires to drop the bomb aimed, he will follow the `sam-e procedure except that he `will close the wing bombs switch.

Droppable 'gas tanks may be 'carried in place of the wing or lfuselage bombs. These tanks are released in the same .manner as the bombs which they replace.

It is the objectcf-the present invention to si-mulate in a ground trainer, 'the selection and firing of rockets andthe releasing yof bombs or droppable tanks 'from an airplane.

'To :attain :this object the trainer is provided with triggers, rocket selector, bomb or tank 'selector switches, master armament switch, T handle bomb release fand Wing bomb armament switches which are-duplicates in appearance of the regular apparatus of the airplanewhic-h the trainer 'simulates and located n similar positions in the cockpit. equipment is modiiied as yrequired to control circuits whereby the functions simulated lby the operations of such vapparatus are electrically -controlied Provision is also made in the trainer rer' simulating thenoise incident to the iiring of rockets.

For -a better understanding "of the invention, reference may be had 'to the following detailed description `when read in connection with the accompanying drawing in which:

Fig. 1 shows in the left 'portion thereof, certain oi the armament controls in the .cockpit of 'the trainer, in the right portion thereof, signaling equipment at an instructln"s` desk and in the 3 central portion thereof, relay equipment responsive to the controls of Figs. 1 and 2;

Fig. 2 shows in the left portion thereof, additional controls in the cockpit of the trainer, in the right portion thereof additional signaling equipment at the instructors desk and in the central portion thereof additional control relays; and, I

Fig. 3 shows circuits for simulating the noise incident to the firing of rockets.

For a complete disclosure of the invention, Fig. 2 should be placed beneath Fig. 1 and Fig. 3 should be placed beneath Fig. 2.`

The rocket selector, designated by the numeral 200 of Fig. 2, comprises a shaft 20| which may be turned by the handle 202 .against the restraint of the helical spring 203 from its normal position marked Salvo to the extreme position marked Pairs The'shaft is held in its selected position by the engagement of the escapement dog 200 withl the escapement wheel 205. The shaft is permitted to return from any set position to the Salvo position under the tension of the spring 203 through the operation of the dog 204 by the solenoid magnet 206. The plunger armature of the solenoid magnet is normally held in its unattracted position by the spring 201. The shaft 20| has secured thereto three commutators 200, 209, 2|0 with which the commutator brushes 2| I, 2|2 and 2|3 cooperate.

The bomb release T handle 2|4l has three positions into which it may be set, in successive ones of which positions the associated A, B and C switches are closed. In the lowermost position,

in. which the switch A is closed, the fuselage bomb is made safe. In the upper position in which the switch C is closed, the fuselage bomb is released. In the middle position in which the switch B is closed, the fuselage bomb is armed and if the handle is thereafter pulled to its upper position to close the switch C, the armed bomb is released. The circuits disclosed in Fig. 3 for simulating the sounds incident to the release of rockets are similar to the sound effect circuits disclosed in the application Serial No. 622,065, of R. I-I. Gumley, filed October 12, 1945, but modied as required to produce the desired soundeifects.

Rocket selection It will be assumed that the pilot desires to simulate the ring of eight rockets in pairs and for this purpose operates the handle 202 of the rocket selector to the extreme right position marked Pairs In this position'no circuits are established for the selector relays 2|5, 2|6 and 2|'I or the counting relays 2|8, 2|9, 220 and 22|, and none of these relays is consequently operated. Under this condition a circuit is established from the battery 264 through the Pairs lamp at the instructors desk, thence over the upper back contact of the relay 2|5, over the upper back contact of the relay 2 I 6 and the upper back contact of the relay 2|'| to ground and the lamp lights to inform the instructor that the pilot has moved the rocket selector handle 202 to its Pairs position. When thereafter the pilot depresses the rocket trigger .222, an obvious circuit is momentarily established for the relay 223 which over'its inner lower contacts establishes an obvious circuit for the rocket trigger lamp 22'l at the instructors desk which lights to inform the instructor that the pilot has depressed the rocket firing trigger.

The operation of relay 22 3. establishes the circuit of the relay 2|8 'if the pilot has operated r upper back contact of the relay 22|.

4 the master armament switch |00 and the battery power switch |0| has previously been operated by the pilot. The operation of switch |0| simulates the application of battery power to the circuits of the airplane which require such power. The operation of these switches establishes obvious circuits for the relay |02 and the relay |03 from battery |50, relay |02 upon operating establishing an obvious circuit over its upper contact and to battery |50 for the master armament lamp at the instructors desk which lights to inform the instructor of the fact that the master armament switch has been operated by the pilot. With the relays 02 and |03 both operated, the operation of the relay 223 as previously described is effective to establish a circuit from ground over the contacts of relay |03, over the lower contacts of relay |02, conductor |04, over the upper contacts of relay 223 and thence over the upper normal contacts and through the winding of the relay 2|0 to battery 265. Relay 2|0 thereupon operates and locks over its upper alternate contacts, over conductor |05, over the normal contacts of the bomb and tank restore key |06 at the instructors desk, to ground over the upper normal contacts of the relay |01.

Relay 2id, upon operating, establishes a circuit for the escape magnet 200 of the rocket selector 200 which may be traced from battery 266 through the winding of such magnet, over the inner upper contacts of the relay 223, over the inner lower contacts of relay 2|0, over the upper back contact of the relay 2 I9, over the upper back contact of the relay 220 and to ground over the The magnet 206 thereupon operates and again releases when relay 223 releases following the release of the trigger 222 to advance the rocket selector to its first step position marker 2--2-4. Relay ZIB also establishes a circuit which may be traced from battery 20d through the 2-away lamp at the instructors desk, over the lower contacts of relay 2|3, over the lower back contact of the relay 2li?, over the lower back contact of the relay 220, over the lower back contact of the relay 22| and to ground over the contacts of the operated rocket control key 220 at the instructors desk. The lamp then lights toinform the instructor that two of the rockets have been ired. Relay 223 upon operating also establishes a circuit for the relay 225 which circuit may be traced from ground over the upper back contact of relay 22 l, over the lower contacts of relay 223 and through the winding of relay 225 to battery 265, whereupon relay 225 operates and over its lower contacts closes an enabling circuit extending to the sound eifects circuit of Fig. 3 for causing said sound effects circuit to produce sounds in the loud-speaker 300, representative of the sound of a rocket leaving the rocket launcher of the airplane. The manner in which the sound effects circuit functions will be hereinafter described.

As soon as the rocker trigger 222 is released the relay 223 releases followed by the release of the relay 225. The release of relay 223 extinguishes the rocket trigger lamp 221 and as previously described, releases magnet 205 of the rocket selector whereby the pawl 204 permits the advance of the ratchet wheel 205 under the tension of spring 203 so that such selector is released one half step toward its normal position. With the rocket selector in this position, a circuit is established from ground overv segment 226 of commutator 2 l0, over brush 2| 3 and through the winding of the 4A relay 215 to battery 265. Relay 215, upon operating, opens the previously traced circuit for the lamp Pairs which becomes extinguished and establishes a circuit which may be traced from ground over the upper back contact of relay 211, over the upper back contact of relay 2HE, over the upper front contact of relay and through the 2-2-4 lamp :at the instructors desk to battery 264-, which lamp becomes lighted to indicate that the rocket selector has been advanced into its 2--2-4 position.

When thereafter the pilot depresses the rocket trigger 222 to iire an additional pair of rockets, the relay 223 and the relay 225 operate over the circuits previously traced. Relay 223, upon operating, again'establishes the circuit of the lamp 221 which again lights and establishes a circuit for the relay 219 which may be traced from ground connected over contacts of relays 103 and 162 to conductor 104, over the uppermost contacts of relay 223, over the lower contacts of relay 215 and over the upper normal contacts and through the winding of relay 219 to battery Relay 219 thereupon operates and locks over its upper alternate contacts to ground on conductor 165 and establishes the circuit of escape magnet 206 of the rocket selector which circuit may be traced from battery 1266 through the winding of such magnet, over the inner upper contacts of relay 223, over the inner lower contacts of relay 219, over the upper back contact of relay 220 and to ground at the upper back contact or relay 221. Magnet 206 thereupon releasesl the rocket selector a half step towards its normal position. Relay 219 also opens at its lower back Contact the previously traced circuit for the 2-away lamp at the instructors desk and establishes a circuit for the 4-away lamp which may be traced from battery 264 through such lamp, over the lower front contact of relay 219, over the lower back contact of relay over the lower back contact of relay 2-21 and to ground over the contacts of key 224.

When the rocket trigger -222 is again released,

relays and 225 release, the rocket trigger lamp 22? becomes extinguished, and vescape magnet 266 releases so that the rocket selector is `released a further half step toward its normal position or into the position designated 2-6. With the rocket selector in this position, the previously traced circuit for relay 215 is opened whereupon such relay releases to open the circuit of the 2-2-4 lamp at the instructors desk and such lamp becomes extinguished. A circuit is now established from ground over segment 228 of commutator 266,' brush 212 and through the winding of the relay 216 to battery. Relay 216 upon operating establishes a circuit for lighting the 6 lamp at the instructors desk which circuit may be traced from ground over the upper back contact of relay 211, over the upper front contact ci relay 216 and through the lamp v2---6 at the instructors desk to battery 264 which lamp lights to inform the instructor that Athe rocket selector has been operated to the 2 6 position.

When thereafter, the pilot depresses the rocket trigger 222 to fire an additional pair of rockets the relay 223 and relay 225 `operate vover the circuits previously traced. Relay 223 upon operating again establishes a circuit for lamp 221 which again lights and establishes a circuit for the relay 22e which may be traced from ground on conductor 104, over the upper contacts of relay V223, over the lower contacts of relay 216 and over 'the upper normal contacts and-through the in its normal vposition does not advance.

winding :of relay 220 to battery 265. Relay 220 thereupon operates and locks over its upper alternate contacts to ground on conductor and establishes the circuit of escape magnet 206 of the rocket selector which may be traced from battery 266 through the winding of such magnet, over the inner upper contacts of relay 223, over the inner lower contacts of relay 220 and to ground over the upper back contact of relay 221. Magnet 206 thereupon operates and releases the rocket selector a half step towards its normal position. Relay 220 also opens at its lower back Contact the previously traced circuit for the 4- away lamp atthe instructors desk and establishes a circuit for the 6-away lamp at the instructors desk which may be traced from battery 264 through such lamp over the lower front contact of relay 220, the lower back contact of relay 221, and to ground over the contacts of key 224.

When the rocket trigger 222 is again released, relays'223 and 225 release, the rocket trigger lamp 22'1 becomes extinguished and escape magnet 206 releases so that the rocket selector is released a further half step to its normal position or into the position designated Salvo With the rocket selector in this position, the previously traced circuit for relay 216 is opened, whereupon such relay releases to open the circuit of the 2 6 lamp at the instructors desk and such lamp becomes extinguished. A circuit is now established from ground over segment 229 of commutator 208, brush 211 and through the winding of the relay 21'1 to battery 265 whereupon relay 21'1 operates. At the same time, the

circuits of the relays 215 and 216 become established over the segments 231 and 230 of commutators 210 and 209 and such relays reoperate. The reoperation of relays 215 and 216 is without function at this time, but the operation of relay 21'1, establishes a circuit for lighting the Salvo lamp at the instructors desk, the circuit of which may be traced from ground over the upper front contact of relay 211 and through the lamp to battery 264 whereupon the lamp lights to inform the instructor that the rocket selector has been advanced to the Salvo position.

When thereafter the pilot depresses the rocket trigger 222 to fire the additional or last pair of rockets, the relay 223 and `the relay 225 operate over the circuits previously traced. Relay 225 upon operating locks over its upper contacts, and over the upper contacts of relay 223 to ground on conductor 104 so that such relay 225 will remain operated as long as relay 223 remains operated irrespective of the fact that the initial operating circuit of relay 225 is opened at the upper contacts of relay 221 upon the subsequent operation ofthe relay 221. Relay 223 upon operating again establishes the circuit of lamp 227 which again lights and establishes a circuit for the relay 221 which may be traced from ground on conductor 104, over the upper contacts of relay 223, over the lower contacts of relay 21'1, over the inner upper contacts o the relay 225 and over the inner upper normal contacts and through the winding of relay 221 to battery 266. Relay 221 thereupon operates and locks over its upper alternate contacts to ground on conductor 05 and establishes the circuit oi escape magnet 266 or" the rocket selector which may be traced from battery 2513 through the winding oi such magnet, through the inner upper contacts or relay 223 and to ground at the inner vlower contacts of relay 221. Magnet 266 thereupon operates but the rocket selector being Relay 22| 'also opens'at its lower back contact'the previously traced circuit for the 6away1amp at the instructors desk and establishes a circuit for the 8away lamp which may be traced from battery 254 through such lamp, over the lower front conrelay 223 will reoperate but with relay 22! still operated at that time, the relay 225 will not reoperate and therefore the sound effects circuit is not operated to simulate the sounds incident to the iiring of further rockets.

l'f the initial setting of the rocket selector switch is other than in the Pairs position, the operation of the circuits is similar to that described above except that thefstarting point of relay operation will be with the relay 2 6 followed by the operation of the relay 2|9 if the selector is set into the 2-2-4 position; will be the relay 2 i'i followed by the operation of the relay 220 if the selector is set into the 2 6 position or will be the operation oi the relays 2lb, 2|6 and 2H,

followed by the operation oi the relay 22| if the selector is set into the Salvo position. Also the Pairs and 2-away lamp will not light and the 2-2-4, fi-away, 2 8 and -away lamp may not light depending on whether the rocket selector switch is initially set in the 2-2-4, 2-6 or Salvo positions.

It will be recalled that when the relay 225 operates, it closes an enabling circuit for the rocket noise4 simulating circuits of Fig. 3. This circuit which is established each time that relay 225 operates in response to the depression of the rocket trigger 222, extends from ground over the lower contacts oi relay 22E, over conductor 232 and through the winding of relay 3?! to battery .itl and relay Sill thus operates. The noise simulatine; circuits comprise the gas-filled or thyratron tube VTi which functions as an oscillator, dual amplifier tubes VT2 and VTlEl each having two units thereof connected in cascade, the preamplier tube VTS and the pentagrid amplifier tube VIt.

Filament heating current is supplied `to the filaments of all the tubes over the supply conductors Bti and 363 which are connected to the secondary winding of the step-down filament supply transformer FT, the primary winding of which transformer is connected to a commercial supply source of 115 volts alternating current. Plate potential is supplied from the +130 volt battery B connected to the plate supply bus-bar 3M, from which potential is supplied through resistors R|, R3, R22 and R135 to the plates of tubes VTi, VT2, VTS and V'IIil` and directly to the plate of the right unit of tube VT||J and through choke coils A and A4 in series to the plate of tube VT3. Potential from bus-bar 33M is also supplied through the potential divider resistors R43 and Rfid to the ground bus-bar 305 from the junction point oi which potential divider potential is supplied to `the screen grid and cathode of tube VTi?. Potential from bus-bar 304 is also applied through the resistors R52 and R50 in series to the ground bus-bar E05 and potential derived at the junction point between such resistors is applied over the upper back contact of ecomes extinguished and magnet 206 8 relay 30|, through condenser C25 to the ground bus-bar 305, whereby the condenser is normally charged. The potential at the plate of tube VT8 is applied over a circuit through condenser CIS and thence in parallel through choke coil A5 and the primary winding of output transformer OT to the ground bus-bar 305.

The ground bus-bar is connected directly to both the grid and cathode of oscillator tube VTI, through resistors R2 and R5 to the control grids of tubes VT2, through resistors Ril and R1 and condensers C2 and Cil to the cathodes of tube VT2, through resistor R3! to the cathode of tube VTS, through the resistor R43 to the cathode of tube VT9, through resistors R25 and R49 to the grids of tube VTI 0 and through resistors RM and R48 to the cathodes of tube VTI The plate of the right unit oi tube VT2 is connected through condenser C8, resistor RM and through the filter comprising choke coil A'I and condensers C2i and C22, connected in parallel with the winding of the volume control rheostat ROC-VOL to ground, the slider of which rheostat is connected to the control grid of tube VTQ. The suppressor grids of tube VTS are connected through resistor R5I and the ROC-Time rheostat to the` ground bus-bar.

Relay 30| when unoperated establishes the previously mentioned charging circuit for condenser C25 over its upper back contact and over its lower back contact connects direct ground through resistor R59 and through the VOL rheostat to the ground bus-bar S so'that there shall be no input to amplier tube VT8. When relay 39| is operated the charging circuit for condenser C25 is opened and a discharge circuit for such condenser is established over the upper front contact of relay Sl through resistor Rel and timing rheostat ROC-Time so that condenser C25 is permitted to discharge at the rate determined by the adjustment of such rheostat. Also with relay 33| operated, the ground `connection to the upper terminal of rheostat VOL is opened and the cathode of the right unit of tube VTIEI which unit functions as a cathode follower is connected through condenser C26, resistor R59 and rheostat VOL to the ground bus-bar 305 so that the output of the cathode follower tube is applied from the slider of rheostat VOL to the control grid of the preamplier tube VTS.

It will be assumed that when the trainer is put into service, plate potential is applied from battery B to bus-bar 364, alternating current is supplied to the primary winding oi filament transformer FT and that amplier 305 and loudspeaker 300 are supplied with operating current. The iilaments of all the tubes now become heated. With plate potential applied through plate resistor Rl, with both its cathode and control grid connected to ground and its filament heated, tube VT! now oscillates and generates random frequencies which are impressed upon the control grid of the left unit of amplier tube VT2 through the condenser-resistance coupling comprising condenser C| and resistor R2. The left unit of tube VT2 being supplied with plate potential connected to its plate through the plate resistor R3, having its grid biased with respect to its cathode by means of the cathode bias resistor R4 and modulated by the output of the oscillator VTI applied to its grid through the coupling condenser CI, the left unit of tube VT2 responds to the output of tube VTI and applies an amplified signal potential upon the grid of the right unit of tube VT2 over a path fromsuch grid through coupling condenser C3.

over the plate-cathode path through the left unit of tube VT2 and through resistor R4 in parallel with condenser C2 tov ground. The right unit of tube VTZ having plate potential connected to its plate through plate resistor R6r and having its grid biased with respect to its cathode by means of the cathode biasing resistor R1 follows the amplified output signal from the left unit of tube VT2 and applies an amplified signal over a path from ground through the cathode biasingv resistor R1 inl parallel with condenser C4 over the cathode-plate path through the right unit of tube VT2, through coupling condenser C8, coupling resistor R4I, through the filter network comprising choke coil A1 and condensersy C2 I, and C22, connected in paralleliwith the winding of volume control rheostatv ROC-VOL and tov ground. Potential from this coupling circuit is now applied from the slider of the volume control rheostat to the control grid of the converter or gate tube VTS.

The grid of VTS is biased with respect to its cathode through the cathode biasing resistor R43 at this time, plate potential is connected to its plate through plate resistor R42 and screen grid potential is connected to the screen grid of such tube through the resistor R44. The tube will not respond to the signal input potential applied `to its control grid at this time, however, if relay 310| is not operated since the suppressor grids of tube VTS' will have ground potential applied thereto through resistor R5 and the timing rheostat ROC-Time.

It will now be assumed that as previously described the pilot has depressed the rocket trigger 222 to re a pair of rockets and that in response to the operation of said key, the relay 225 has operated and in turn has caused the operation of relay 30|. Relay 30|, upon operating, connects the charged condenser C into a discharge path extending frorn ground through such condenser, over the upper front contact of relay through resistor R5I and rheostat ROC-Time to ground. At the instant the discharge circuit is established, the full-charge potential of condenser C25 appears as a positive potential on the suppressor grid of tube VTS, whereupon tube VTS becomes conducting and impresses its output upon the control grid of the left unit of tube VTI!) through the condenser-resistor coupling comprising condenser C23 and resistor R45. The left unit of tube V'II having plate potential applied to its plate through the plate resistor R46 and having its grid biased with respect to its cathode by the cathode bias resistor R41, now responds to the output signal from tube VTS and applies an amplied signal potential upon the grid of the right unit of tube VTIO over a path from such grid through coupling condenser C24 over the platecathode path through the left unit of tube VTI and through resistor R41 to ground. The right unit of tube VTIO having plate potential applied to its plate and its grid biased with respect to its cathode acts as a cathode follower and impresses its output through the coupling condenser C26 and resistor R59 upon the control grid of the preamplifier tube VTS. The gain of this tube may be regulated by the gain control rheostat VOL.

The tube VTSA serves to further amplify the signal and to impressv it through the output transformer OT, upon the loudspeaker amplifier unit 300 which further amplies the signal and applies the amplified signal upon the. loudspeaker 300,. The noise emitted by the loudspeaker will be a loud hiss.

As the charge on the condenser C25 becomes dissipated through the resistor F5I and the timing rheostat ROC-Time, the potential applied to the suppressor grid of tube VTS will slowly decay. The time of decay is determined by the setting of the timing rheostat. As the potential applied to the suppressorl grid of tubev VTS diminishes, the conductivity of the tube will diminish until it will cease when the condenser C25 becomes suiiciently discharged to reduce the potential on the suppressor grid of tube VTS to a` value such that the tube becomes blocked. Thus as the conductivity of tube VTS decreases, the intensity of the Whoosh sound emitted by the loudspeaker 300 decreases simulating realistically the sound of a rocket as it is discharged and pro,- gresses away from an airplane.

When the relay 30| releases,y following the release of the relay 225, the discharge path for condenser C25 is opened and the condenser again charges over its charging path. Also at its lower back Contact relay 30| by connecting ground to the coupling circuit between the cathode follower unit of tube VTI0 and the preamplier tube VTSV prevents any inputI to `the tube VT8 and thereby to the loudspeaker 300 as long as relay 30| remains unoperated or untilthe pilot again operates the rocket trigger 222 to simulateV the firing of other rockets.

Bomb releasing simulation It will now be assumed that the pilot desires to simulate the dropping of the wing bombs in a safe condition. Hev will rst ascertain if the wing bomb key |08 is in the safe position, that is, open, and will then close the right tank switch |09 or the left tank switch ||0 or both. He will next close the master armament switch |00 and pressv the bomb trigger I I I. With switch |08 open the relay II2 and the relay I|3 will both be unoperated and the wing bomb safe lamp ||4 at the instructors desk will be lighted over a circuit extending from battery therethrough and tov ground at the upper back contact of relay IIS. The closing of the master armament switch |00 will cause the operation of the relay |02 and the lighting of lamp II5 at the instructors desk as previously described.

If the left tank switch ||0 has been closed, the relay IIB will be operated over a circuit extending from ground over the contacts of switch 0, through the winding of relay IIE and to battery |50, or if thel right tank switch |09 has been closed, the relay II'I will be operated over a circuit extending from ground over the contacts of switch |09, through the winding of relay I|1 and to battery |50, and if both switches have been operated, relays IIE and II'I will both operate. If relay IIE is operated, ay circuit is established from ground over its upper front contact through the left wing bomb release lamp II8 at the instructors desk and then to battery |50 and lamp I I8 will light. If relay |I1 is operated a circuit is established from ground over its upper front contact through the right wing bomb` re-y lease lamp IIQ at the instructors desk to battery |50 which lamp will light. The lighting of either or both of these lamps informs the instructor that, the pilot proposes to release such wing bombs. Under the assumption that there is a wing load of bombs, the key |20 at the instructors desk will be operated to its upper position and the relay 12| will not be operated.

When the pilot depresses the bomb trigger I I I, a circuit is closed for the relay |22 extending from ground 4over the contact of trigger III and through the winding of relay |22 to battery |50 which operates and establishes a circuit for the bomb trigger lamp |23 at the instructors desk extending from ground over-the upper outer contacts of relay |22, through the lamp |23 and to battery |50, which then lights to inform the instructor that the pilot has operated the bomb trigger. If the relay ||6 has been previously operated, then when Vrelay |22 operates, a circuit is established from ground on conductor |04, over the inner contacts of relay |22, over the lower contacts of relay ||6, over the inner upper normal contacts and winding of the relay |24 to battery |50, whereupon relay |24 operates and locks over its inner upper alternate contacts to ground over conductor they contacts of key |06 and the back contact of relay |01.

At its upper vouter front contact, relay |24 establishes a circuit from ground, over the upper back contact of the relay |25, over conductor |26 and through lamp 233 at the instructors desk to battery 264, which lamp lights to inform the instructor that the left wing bomb has been released in a, safe condition. Had the relay ||1 been operated, then upon the operation of the relay |22, a circuit would have been established from ground connected as previously described by the operation of relays |02 and |03 to conductor |04, over the inner contacts of relay |22, over the lower contacts of relay ||1, over the inner upper normal contacts and through the winding of the relay |21 to battery and relay |21 would have operated and locked over its inner upper alternate contacts to ground over conductor |05, the contacts of key |06 and the back contact of relay |01 and would have established a circuit from ground over the outer upper front contact of relay 21, over the back contact of the relay |28 and through lamp |29 to battery |50. Lamp |29 would therefore have lighted to indicate to the instructor that the right Wing bomb had been released in a safe condition.

If relay 24 is operated as above described, a circuit is established from ground over the inner lower contact of relay |24, over conductor |30 and through the winding of the relay 234 to battery 264, or if relay |21 is operated, a circuit is established from ground over the inner lower contacts of relay |21, over conductor |3| and through the winding of the relay 235 to battery 264. When relay 234 operates, it closes a short circuit around resistorV 238 in a circuit which extends from ground through resistors 236, 231 and 238 in series and over conductor 239 to the circuits of the trainer which produce the indicated air speed and angle of climb e'ects of simulated flight. The short-circuiting of resistor 238 serves to produce the increasein the indicated air speed and angle of climb which would result in an airplane from the releasing of the left wing bomb. Similarly the operation of relay 235 short-circuits resistor 231 which produces a similar increase in indicated -air speed and angle of climb which would result in an airplane from the releasing of the right wing bomb, If both wing bombs are released, then both relays 234 and 235 would be operated causing the short-circuiting of both resistances 231 and 238 and a resultant larger increase in the indicated air speed and angle of climb which would result from the release of both wing bombs.

The release of the bomb trigger releases relay |22 andthe opening of switches |09 and ||0 releases relays ||1 and ||6 which in turn extinguish the lamps |29 and 233. Relays |24 and I 21. however. remain locked operated until the l2 relay |01 is operated in a circuit extending from battery |50 through the Winding of relay |01 and over the contacts of key |34 to ground when key 34 is operated.

If tanks had been mounted in place of wing bombs, their release is the same as just described.

To simulate the safetying of the fuselage bomb, the pilot operates the T-handle 2|4 to a position in which the A switch is operated, thereby establishing an operating circuit for the relay 240 which extends from ground over the contacts of switch 2|4 closed in the A position, through the winding of relay 240 and to battery 264. This relay, upon operating, causes the lighting of the lamp 24| at the instructors desk over a circuit extending from ground over the upper front contacts of relay 24B, through lamp 24| to battery 264 to inform the instructor that the T-handle has been moved to the bomb safe position. To release the fuselage bomb in a safe condition, the T-handle is pulled up to a position in which the C switch is operated, thereby establishing a circuit for the relay 242 extending from ground over the contacts of switch 2|4 in its C position, and through the winding of relay 242 to battery 264 which upon operating causes the lighting of the release lamp 243 at the instructors desk over a circuit from ground through the upper front contact of relay 242 and through lamp 243 to battery 264, as a signal that the T--handle has been moved to its release position. Relay 242, upon operating, prevents the operation of the relay 244 by opening the circuit thereof at its upper back contact and establishes a circuit for the relay 245 which may be traced from battery 265 through the winding of relay 245, over the lower contacts of relay 242 and to ground over the middle upper back contact, of the relay 246, Relay 245, upon operating, locks over its inner upper contacts to ground over conductor |05, the contacts of key |06 and over the back contact Iof relay |1, establishes over its inner lower contacts a circuit for lighting the lamp 241 at the instructors desk extending from ground over the inner lower front contact of relay 245 and through lamp 241 to battery 264, as a signal that the fuselage bomb has been released in a safe condition or if a gas tank has been mounted in the bomb rack that the tank has been dropped and over its upper outer contact establishes a circuit for the relay 246 which may be traced from ground over the contacts of relay 245 and through the winding of relay 248 to battery 264.

Relay 248, upon operating, shunts the resistor 236 in the circuit extending to conductor 239, thereby causing an increase in the indicated air speed and angle of climb which would result from dropping the fuselage bomb or tank.

Relay 245 at its outer lower back contact opens the circuit controlled by the bomb trigger for operating the relay 246, which circuit may be traced from battery 264 through the winding of relay 246, over the outer lower back contact oi relay 245, the lower contacts of relay 244, the upper back contact of relay 246, the lower contacts of relay 252, conductor |36, the inner upper contacts of relay |22, conductor |04, the lower contacts of relay |02 and to ground over the contacts of relay |03, so that such relay may not be operated by the operation of relay 22 in response to the operation of the trigger.

To drop the wing bombs in an armed condition, the pilot will operate the right tank switch |09 or the left tank switch |0 or both, will close the wing bomb arming switch |08 and the master amano armament switch thereby .closingv the. previously traced circuits for the relay ||1,. the relay ||6` and the relay |02 andi establishing a' circuity for the relay |L|2 which may be traced from ground over the contacts of switch |08 and through the winding of relay |'|2: to battery |597'. Relay ||2 upon operating establishes a circuit for the relay ||3y which may be traced from ground over the contacts of relay ||2 andthrough the winding of relay H13 to battery |50. Relays H61, |1 and |02', upon operating, establish the circuits of the lamps IIS, |15 and |.|5, respectively, previously described and relay |3 establishes over its inner upper contacts a circuit for the. wing tank arming lamp |48 at the instruct'ors desk extending from ground over the inner upper contacts of relay |'|3 and through lamp vlitt tov battery |50 to inform the instructor that one or both. of the wing bombs is to be dropped in an armed condition. Relay ||3' also establishes a circuit from groundv over its upper outer fron-t contact, over the lower normal contacts of the relay |21 and through the winding. of the relay |28 to battery |50', thereby causing the operation of relay L21?.` and establishes a circuit from ground over the contacts of relay |03, over the lower contacts: of relay H3, over' the lower normal contacts of the relay |24' and through the. winding of the relay |25 to battery |50 thereby causing the operation of relay |25.

If now the pilot depresses thebomb trigger l l, thereby operating the relay |22,.`the trigger lamp |23 at the iustructors desk is lighted and if the relay |-1 hasbeen operated in yresponse to the operation of the right tank switch |09, a circuit is established from ground connected to conductorv |04V over the upper contacts of relay |03 and the' lower contacts of relay |0'2, over the inner contacts of relay |22, over the lower contacts oi relay H1, through theI upper normal Acontacts and winding of the relay |21 to battery |50 and relay 521 operates, locks over its inner upper alternate contacts to ground over conductor |05, the contacts of key It and the back contact of relay |01, completes the locking circuit of the relayI |28 which extends over the lower alternate contacts of relay |21' to ground over the lower contacts of relay |23 and establishes a circuit from ground over its middle uppercontacts, over the upper front contact of relay |28 and throughv lamp |32 to battery |50. Lamp |32' lights as a signal to the instructor that the right wing bomb has been released in an armed condition.

Similarly, if the relay H6 has been operated in response to the operation of the left tank switch |10., a circuit is established upon the operation of the bomb trigger from ground connected to conductor |04 over the upper contacts of relay H23 and the lower contacts of relay |02, over the inner contacts of relay |22, over the lower contacts of relay l I8, through the inner upper normal contacts and winding of the relay |24 to battery |50, and relay |24 operates, locks over its inner upper alternate contacts to ground over conductor E05, the contacts of key and the back contact of relay |01, completes the locking circuit for the relay |25 which extends over the lower alternate contacts of relay 524 to ground over the lower contacts of relay |25, and establishes a ci'rcuit irom ground over its middle upper contacts, over the upper front contact oi relay |25, over conductor |33 and through the lamp 249y to battery 264. Lamp 249 lights as a signal to the instructor that the leit wing bomb has been released in an armed condition. After the bomb trigger has. been pressed and released and the switches |019 and ||0 have been opened, relays |6, ||1Y and |22 will release, but relays |24, |21, |25 and |28 will remain locked in their operated conditions until the instructor removes ground from conductor |05 by causing the operation of the relay |01' through the operation ci key |34. With these relays locked operated, the lamps |32 and 249 remain lighted as signals to inform the instructor which bombs have been dropped in an armed condition.

To prepare the fuselage bombv for armed release, the pilot operates the T--handle 2|4 to its intermediate position in which the contacts oi switch B are closed thereby establishing a circuit fo-r the relay 244, which circuit extends from ground over the contacts of switch B, over the upper back contact of the relay 242 and through the winding of relay 244 to battery 264. Relay 244, upon operating, closes a circuit for lighting the lamp 250'- at the i-nstructors desk extending fromV ground over the upper contacts of relay 244 and through lamp 250 to battery 264 to inform the instructor that the pilot has moved the T- handle toits arming position. Relay 244 also at its 4lower contacts prepares the circuit of the relay 246 -to be later described. Also to prepare thefiusel-age bomb for armed release, the pilot closes the center tank switch 25| thereby establishing a circuit for the relay 252 extending from ground over the contacts of switch 25| and through the winding of relay 252 to battery 264 which, over its upper front contact and conductor 253 establishes the circuit of lamp |35 which lights to inform the instructor that the pilot intends to release the fuselage bomb. With the master armament switch |00, previously operated and relay |02 thus operated, when the pilot now depresses the bomb trigger l and relay |22 operates, a circuit is established from ground over thev contacts of relay |03, over the lower contacts of relay |02, the inner contacts of relay |22, conductor 38, over the lower contacts of relay 252, the upper back contact of relay 240, the lower contacts of relay 244, the lower back contact of relay 245 and through the winding of the relay 246 to battery. Relay 246 thereupon operates and locks over its inner lower contacts to ground over conductor |05, the contacts of key |0t and thev back contact of relay lill, closes a circuit over its lower contacts through lamp 254 to battery 204,l which lights to inform the instructor that the fuselage bomb has been dropped and establishes a circuit from ground over its inner upper' contacts through the winding of relay 248 to battery 264 which thereupon operates to shunt out resistor 234 whereby the indicated air speed and angle of climb circuits of the trainer are controlled to show the increase in air speed and angle of climb which would be incident to. dropping the fuselage bomb.

If after the dropping of all the bombs has been simulated, it appears desirable to repeat the process of dropping the bombs, the instructor can replace the bomb load by operating the key It thereby releasing any of the armament relays |24, |25, |21, |28, 2.45 and 246 which may have been locked operated under the control oi the relay |01. Also after the trainer iiight has been completed and the trainer is again on the ground, the operation of the reload and recharge key |35 wil-l release all of the operated armament relays that have been locked under the control of the relay |01.

Circuit breaker ooerloaol simulation Switches iill, its, il@ and 25| are of the circuit breaker type, that is, they will open automatically on a current overload condition. To simulate these overload conditions, keys are provided at the instructors desk for connecting a battery directly to the switches.

It will be assumed that the switch m9 has been closed by the pilot resulting in the operation of the relay ill and that to simulate the blowing of this circuit breaker switch, the instructor closes the overload switch |32. The closing of switch |37 applies battery directly over the left contacts thereof to a point between the circuit breaker switch lilS and the winding of relay At the saine tirne a circuit is established from battery |55 over the right contacts of the switch |31, through the upper winding of the relay |38 and to ground at the upper front contact of relay I il. Relay its will therefore operate before the connection of the direct battery to the circuit breaker switch itil causes such switch to blow open and open the circuit relay l il. Relay l 3B, upon operating, partially closes a locking circuit from battery i5@ through its lower winding and inner lower contacts which becomes completed to ground over the back contact of relay Il as soon as relay ill releases. Relay ist being slow-to--release will not release during the interval between the opening of its initial energizing circuit at the upper front contact of relay I il and the completion. of its locking circuit at the back contact of relay ill, With relay lll' released and relay |38 operated, a circuit is established from. ground over the back contact of relay lll and over the lower contacts of relay it through the lamp |39 to battery Eil. Lamp E39 will then light to inform the instructor that the circuit breaker switch |29 has been blown. At the same time the release of relay i il ezrtinguishes lamp i i2 at the instructors desk.

When the instructor opens the overload switch i3?, relay il? will remain released and relay |38 will remain operated. When the pilot again closes the circuit breaker switch |532, relay I Il will again operate opening the locking circuit of relay |38 whereupon relay i 33 will release opening the circuit of lamp i3@ which becomes extinguished and again causes the lighting of lamp H9.

The relay ltd functions with relay H6, circuit breaker switch i iii and overload switch |49 and lamp |22 at the instructors desk; the relay .|43 functions with relay l i3, circuit breaker switch i lil and overload switch llfi and lamp |25 at the instructors desk; and the relay 255, functions with relay 252, circuit breaker switch 25| and overload switch 2155 and lamp |25 at the instructors desk in a manner similar to the operation of the relay itil just described.

The instructor is provided with two keys and 257, each of which is a three position key. If the key l2@ is in its center position, representative of the absence of either a bomb or fuel tank load on the wings, a circuit is established for the relay extending from ground over the normal contacts of key |28 and through the winding of i'l to battery |59, which operates to close circuits over conductors |35 and |3| through the windings of relays 23d and 235 to battery 255i which operates to short-circuit resistors itl and 238 from the circuit over conductor 22 so that the indicated air speed and angle of climb circuits of the trainer function in a manner representative of no wing load. If the switch 257 is in its center position, representative of f close its lower contacts, relays lili,

the absence of either a bomb or fuel tank in the bomb rack of the fuselage, a, circuit is established from ground over the contacts of such switch through the winding of relay 222 to battery 22a so that the indicated air speed and angle of climb circuits function in a manner representative of no fuselage load.

When the switch |22 is operated to open its upper contacts, a bomb load condition for the wings is set up and relay |2| is released to release relays 23d and 23'5 and when the switch 2557 is operated to its lower position, a bomb load condition for the fuselage is set up and relay 22S is released. When the switch l2@ is operated to 225i and are released and a condition is set up representative of a fuel tank load on the wings and when the switch 25'! is operated to its upper position, relay 2138 is released and a condition is set up representative of a fuel load on the fuselage.

The pilot is provided with a fuel selector valve by means of which fuel may be trunked from any of the fuel tanks of the airplane to either one or both of the engines. This Valve is simulated in the trainer by the switch 253. In the WD position of the switch, the trunking of fuel from the wing tanks is simulated. In this position a circuit is established for the relay 259 extending from ground over the contacts of switch 2553 and through the winding of relay 259 to battery 251i which closes a circuit for lamp 255 at the instructors desk extending from ground over the outer lower contacts of relay 259 and through the lamp 26|] to battery 264 to inform the instructor that fuel is being taken from the droppable wing tanks. With the switch |25 at the instructors desk set into its `lower position, a circuit is established from ground over the lower contacts of such switch, over the upper back contact of the relay |21, the upper back contact of the relay i255, conductor |47, over the contacts of relay 259 and through the winding of the fuel supply relay 25| of the trainer to battery 251 and relay 2t| operates to indicate that fuel is being supplied to an engine or engines from the droppable wing tanks. Thereafter when the pilot causes the dropping of either of the wing tanks after the fuel is withdrawn therefrom and either the relay lil or the relay |24 becomes operated, the circuit of the relay 26| will be opened and the engine being supplied from such tank will stop unless a switch over to another tank is made by a resetting of the fuel tank selector switch 25s prior to dropping the wing tanks. The trainee will know that the stopping of the engine is being simulated by the stopping of the simulated engine noise and the operation of the tachometer of the trainer.

In the FD position of the switch 253, the drawing of fuel from the droppable fuselage tank is simulated. In this position, a circuit is established for the relay 252 extending from ground over the contacts of switch 252 and through the winding of relay 252 to battery 2%, which closes an obvious circuit for the lamp 223 at the instructors desk to inform the instructor that fuel is being taken from the droppable fuselage tank. With the switch 25ll at the instructors desk set into its fuselage tank position, a circuit is estabn lished from ground over the upper contacts of such switch, over the upper back contact of the relay 42436, over the middle lower back contact of the relay 245, over the lower contacts of rei-ay 262 and through the winding of the relay Rill to battery. Relay 25| thereupon operates to indicate that fuel is being supplied to an engine or engines from the droppable fuselage tank. Thereafter, when the pilot causes the dropping of the fuselage tank, after the fuel has been taken from it and either relay 245 or 246 is operated, the circuit of the relay will be opened and the engine being supplied from such tank will stop unless a switch over to another tank is made by a resetting of the fuel tank selector switch 25B prior to dropping the fuselage tank.

What is claimed is:

l. In an aircraftl trainer wherein the operation of the armament of an airplane is simulated, a train of counting relays, an instructors desk, lamps at said desk responsive to said relays to indicate the simulated release of successive rockets, a rocket selector switch, means for advancing said switch step-by-step in response to the operation of successive ones of said counting relays, a plurality of relays successively operable in successive positions of said switch, a trigger key, and means eiifective upon successive operations of said key and upon the successive operation ci' said latter relays to cause the successive operation of said counting relays.

2. In an aircraft trainer wherein the operation of the armament of an airplane is simulated, a train of counting relays, an instructors desk, lamps at said desk responsive to said relays to indicate the simulated release of successive rockets, a rocket selector switch, means for advancu ing said switch step-by-step in response to the operation of successive ones of said counting relays, a plurality of relays successively operable in successive positions of said switch, other lamps at said instructors desk responsive to said latter relay to indicate the position to which said switch has been moved, a trigger key, and means effective upon the successive operations of said means and upon the successive operation of said latter relays to cause the successive operation of said counting relays.

3. In an aircraft trainer, wherein the operation of the armament of an airplane is simulated, a train of counting relays, an instructors desk, lamps at said desk responsive to said relays to indicate the simulated release of successive rockets, a rocket selector switch manually settable into a plurality oi positions representative oi the selected release of different groups of rockets, means for releasing said switch from its set position step-by-step in response to the opera-tion of successive ones of said counting relays, a plurality ci relays successively operable in successive positions ci said switch, other lamps at said instructors desk responsive to said latter relays to indicate the position to which said switch has been manually set, a trigger key, and means effective upon successive operations of said key and upon the successive operation oi said latter relays to cause the successive operation of said counting relays.

4. In an aircraft trainer wherein the operation of the armament of an airplane is simulated, a train of counting relays, an instructors desk, lamps at said desk responsive to said relays to indicate the simulated release of successive rockets, a rocket selector switch, means for advancing said switch step-by-step in response to the operation of successive ones of said counting relays, a plurality of relays successively operable in successive positions of said switch, a trigger key, means effective upon successive operations of said key and upon successive operations of said latter relays to cause the successive operation of said counting relays, and a lamp at said instructors desk responsive to said trigger key for indicating to the instructor each operation of said key.

5. In an aircraft trainer wherein the operation oi the armament of an airplane is simulated, a train or" counting relays, an instructors desk, lamps at said desk responsive to said relays to indicate the simulated release ci' successive rockets, a rocket selector switch, means for advancing said switch step-by-step in response to the operation oi' successive ones oi said counting relays, a plurality of relays successively operable in successive positions of said switch, a trigger key, means effective upon successive operations of said key and upon successive operations of said latter relays to cause the successive operation of said counting relays, and means responsive to the operation or said trigger key to simulate the sounds incident to the discharge of each rocket.

6. In an aircraft trainer wherein the operation of the armament of an airplane is simulated, a master armament switch, a train oi counting relays, an instructors desk, lamps at said desk responsive to said relays to indicate the simulated release of successive pairs of rockets, a rocket selector switch manually settable into a plurality of posititions representative of the selective release of different groups of rockets, means for releasing said switch from its set position stepby-step in response to the operation of successive ones of said counting relays, a plurality of relays successively operable in successive positions of said switch, other lamps at said instructors desk responsive to said latter relays to indicate the position to which said switch has been manually set, a trigger key, means responsive to the operation of said master armament switch and effective upon the successive operation of said key and upon the successive operation of said latter relays to cause the successive operation of said counting relays, a lamp at said instructors desk responsive to said trigger key for indicating to the instructor each operation of said key, and means responsive to the operation of said trigger key to simulate the sounds incident to the discharge of each rocket.

7. In an aircraft trainer wherein the operation of the armament of an airplane is simulated, a master armament switch, selecting switches for simulating the selection of wing supported bombs for release in either an armed or a safe condition, a further switch operable to determine if the selected bombs are to be released in a safe or armed condition, a trigger key, relays responsive to the conjoint control of said master armament switch, said selecting switches and said key, an instructors desk and lamps at said desk responsive to the operation of said relays if said further switch has not been operated to indicate to the instructor that said bombs have been released in a safe condition.

8. In an aircraft trainer wherein the operation oi the armament of an airplane is simulated, a master armament switch, selecting switches for simulating the selection of wing supported bombs for release in either an armed or a safe condition, an instructors desk, lamps at said desk responsive to said switches to indicate which oi said wing bombs is to be released, a further switch operable to determine if the selected bombs are to be released in a safe or armed condition, a trigger key, relays responsive to the conjoint control of said master armament switch, said selecting switches and said key, and lamps at said desk responsive to the operation of said relays if said further switciihasnot.beennseato indicante..

the# instructonthatthe. indicated bombs havel been released in a safe condition.

9.` I-nan aircraft.trainerlwhereinwthe operation ci? the.l armament offxan-airplaneis simulated, a master armament- Switchs selecting.. switches for simulating theselectionoiwing..bombs forrelease ineitlieran armedona salia-condition, a further..

switchoperable-todetermineif thefselected bombs are to. be released .ina safe.v orarmed condition, aerelay--responsive .ta said@ latter. switchI if said bombs. are to be released-in. an armed4 condition, a-l trigger key?. re1ays..responisive..to.. the conjoint operationvv of saidfmaster. armament switch, said selectingswitches. and:saidkey., an instructors desk. andr lamps.. at.l said= desky responsive. to .theconjoint. operation.. of i said-1 first.- and said latter.

relays if said furthenswitch has. beenoperated to..ind.icateA to... the.. instructor thatA said bombs have'. been releasedfsin .an armed condition.

10; Inan` aircraft-trainer wherein the operation=.of.. the` armament ot an` airplaneissimulatede amastenarmamen-aswitchg. selecting-switches fon simulating the. i selection. of wingA supported bombs'`v` or fuel.:tankstfortreleasa. anl instructors desk; a switch. atl said desk forl determining Whethertbombsor fuelftanksiare .assumed to be carriedinuthe wing.. racks,-. a fuel. selector switch operablerbyetlie Ypilot tors'imulate the selection. of-.fuelpta'nks for-connection.tor the assumed en. l

gines oiftiie. trainer, means .operable .under the joint. control off-said?. fuel. selector.. switch. and said... switcti.. at; the..desk-wheni.said fuel selector switch-.is set intea position representative of the-selection..ofidroppable wing.tanks. andthe instructor-:thas operated :said-@switch at .the desky to representftheioperati'on,.otamengine by fuel.

drawn. fromttheuwingtanks, anlampI at the instructoris desk. responsive.. te. the operation.y of said... fuelr tan-k-` selection-switch. to..indic'ate the selection of A1 the Awingftanks` for.fue1` supply, a trigger key,4 relaysiresponsive Ato. theV conjoint control, ofysaidimasten. armament switch, said mst-.mentionedvselectingtswitches.and said trigger. ,key-for, y1e1easing.-said engineoperating simulation means representative of the stoppagefof.

fuell :supplyfto theienginecinci-de'nt 1to1 ,the dropping,- of. the dno'ppable wing,L tanky and lamps at said instructors deske responsive to.. .said relays teindicate.. to. ,thei instructor v`that the. wing- Vtanks hayefbeendroppedf.

1l. In an.aircraft?traineraudit-:reinlv the. operation oitheatmamentof an arplaneis simulated,

first.positionI ffonsimulatingithe saietying. of the fuselaeeibomb... intoeaiseecncl.:position for. simi. latineI the anninef said.l0Qmb,;.-and. intoa third pesiiioeffetsiinuiaimeth releasineof.saidboma.

relay Seietireiymraiie;inutile SeveralA positieilsi Said-handle aninetriletors. desk, lamps. said desk responsive to saidrelays-toindicate,

at iiiepesiiion.- iritqwliifih Saisithari-diehas been operated.; aiamp -at..said inSiruCtQrs desk,..and. a

relay ,responvsivleztothe operationqof that; one ofl I saiddirstl relays ,which is operated when .said

handle .is moved .to .its thirdr releasing position directly fronilitszrst orsafetYngDition for. lighting said-.latterlmpol indicating tothe said.1 relays tof.l indicate. the positioninto which?. saidxhandlefhas been operated-. a bomb trigger..- key, a relayJ :responsivectov .the-conjoint operation ocfv said masten armamentswitch', said# selector.

switch and-said .trigger key. andnonet of. said first; relays if saidf .handlethas been operated inta itsv secondv or lvarmingiposition,L and a lamprcsponsixze'fl to.I the. operationzoftsaid latter relayl to.. indicatav to...theinstructon1whenzthe releaseof the bomba..

in.. an armed` conditionfis simulated;A

13. In an aircraft trainer. wh'ereinfthe. opera.U tionofthetarmament fof. anoailnplane lis simulated; an-.instructorsdesk;A a'. switcinat` saidrdesk: for. determiningrwhether ..-a..,box nlo on. a fuel. tanks is assu-medita becarriedigbeneath the; fuselage,l

a fuel tank-:selector handle operable-by .the pilot..

to.l simulate.: tne-selectionoof fuelftanks for con-` nection to.- thetassumed: engineof fthe.. trainer, a.. selector., switch; .controllectbysaidshandle means-.t operable when. the.: latter. switchgis.: set into a1.

position` repneserrtativelof theselecton ofa` drop.h

pable.. `fuselage tank-andi thefzin'structor has. ope erated ;said1.swtch at saidffdesk-...toi .represent the L Operation oi` amengine by .fueltdrawnfrom. the a fuselage. tank-,f alamo at.-.the1,instructors .desk responsixe .to theaoperationoisaidA fuel tankv sev:

f lector Switch-ttosindicate;the simulation. of the selection of the fuselage tank fonfvfiielzsupply,

a. fuselage.bomb:ycontrolihandle@operable into .a position :f or .indicating .ftheisimulationnoi release.

ing.. the droppahie.- fuselage. tank; a.. relay;4 re monsite :to the operetionffoff -said :handle a lampi.

at;seid;.desk :responsive tothe-,Operation 0i -Saidz relayl to iridiaiie'` to.;` therinstructor; thatr saidj handle has been;,operated.-to-i ts bomb release.. posiisioiii4 and l,aJ relay resppnsi-ye-.tofthe operation.

of said-.1'irst relay for-releasingsaid engine op,-

eratingsimulation means representative of tloestopping of fuel;supply-to4 tha-engine incident, to the droppingofthe-droppableltankand a lamp;l

atisaid instruotorsdesk responsiyeto said lat.

`Iter, relaytoindicatetd.the-:instructor that the...

fuselagetanklhas dropped.

RUssELnB.. BUCHANAN.

ERENCES CITED The following references are offrecordyin the nie? of.tl1i.s patent-.Iv-

UNITEDSTATESTPATENTS 

